In orthopedic surgery involving an extremity, a bloodless field is desirable. Microsurgery continues to increase and a bloodless field is even more important for this type of fine work. The typically used practice is to elevate the limb so that as much blood as possible drains by gravity. Then an elastic or gum rubber bandage of the Esmarch or Martin type is used to exsanguinate the hand or foot. The bandages which are two to four inches wide are wrapped in a spiral around the extremity to squeeze out the blood at a tightness determined by the physician or assistant preparing the extremity. There is no way to determine the pressure being applied to the extremity. Also, the wrapping takes some period of time to wind the bandage in an overlapping spiral around the extremity. The manipulation of the arm or leg during the wrapping can impart additional distress on an injury in the case of post-accident surgery.
The various texts on orthopedic anesthesia recognize this type of exsanguination with a bandage as the state of the art method. See Campbell's Operative Orthopaedics, (Sixth Ed.) Edmonson and Crenshaw Eds. pp. 113-115; and Anesthesia for Orthopaedic Patients by Alan Loach, pp. 11-14. The preferred tourniquet is a pneumatic cuff and the texts describe improvements in this type of tourniquet since pressure can be monitored and maintained at a certain desired level. Timing devices and alarms can be used with the pneumatic cuff. The pneumatic cuff is usually operated by a pressure line in the hospital or a cylinder of compressed gas. The tourniquet pressure is applied after the limb is wrapped and is inflated to a pressure higher than systolic arterial pressure for the arm. The texts devote considerable discussion to the length of time a tourniquet can be used safely and the damage to nerves and vessel which can occur as well as ischemic tissue damage.
For operations lasting more than 1 to 11/2 hours, the tourniquet needs to be released to avoid damage and the wrapping procedure is repeated. When the tourniquet is released after or during surgery, there is a dramatic increase in blood flow. This causes hyperaemia which is relieved by compression dressing and elevation of the limb. A complete exsanguination as possible is also necessary for a regional block of an extremity for intravenous injection of local anesthesia. The proper dosage of anesthesia will be diluted by residual blood fluid in the extremity if exsanguination is not complete. The use of the local anesthetic without the ability to determine the proper dosage is undesirable.
Great concern is placed on the preparation and monitoring of the limbs which are isolated and exsanguinated for surgery. The tourniquet usage has been improved, but the initial exsanguination of the limb prior to tourniquet inflation to maintain the bloodless state is rather primitive bandage wrapping with no measurable controls on the pressure applied.